Lightly brush a 10-inch nonstick skillet with some of reserved butter and heat over medium heat until hot. Pour in 1/4 cup batter, immediately tilting and rotating skillet to coat bottom, and cook crêpe, turning once, until just set and golden, about 1 minute total. Transfer to a plate. Make 7 more crêpes, stacking them.

Brush each crêpe with 1 teaspoon
butter and sprinkle with 1 teaspoon sugar, then fold twice to form a triangle.

Heat 2 teaspoons each of butter and sugar with a pinch of salt in skillet until sugar has dissolved, then cook 4 crêpes, turning once, until golden brown. Repeat with remaining butter, sugar, and crêpes.